Downhole well conditioning tool

ABSTRACT

A downhole well conditioning tool for self-stimulating a well is provided. The down hole tool is a multi-stage stacked self-exciting tool that can alter a relatively steady flow of incoming fluid into pulsating fluid streams of rapidly cycling high and low pressure without the use of moving internal parts. The downhole tool can include a first stage operative to receive a steady flow of pressurized fluid though an inlet and discharge a pulsating fluid flow and a second stage connected to the first stage and operative to receive the pulsating fluid flow from the first stage and increase the pulsations of the fluid flow before the pulsating fluid flow is discharged out of the second stage.

The present invention relates to a downhole well conditioning tool forstimulating a well and more particularly to a multi-stage stackedself-exciting tool that can alter a relatively steady flow of incomingfluid into pulsating fluid streams of rapidly cycling high and lowpressure without the use of moving internal parts.

BACKGROUND

In a typical oil and gas well, the well itself will typically have acasing inside the well bore. This casing serves to maintain theintegrity of the well but it also separates the oil or gas reservoirfrom the inside of the well. In order to produce oil or gas from thewell, the casing must be “perforated” or in other words have holes madein the casing so that oil or gas from the reservoir can flow throughthese perforations into the interior of the well. Typically, theseperforations are made with a perforation gun which carries a number ofexplosive charges and is lowered down the well to the desired positionbefore being fired off and creating these perforations.

However, before oil and gas can flow well through these perforations,the perforations often have to be cleaned out. These perforations canfill with cement or other material as a result of the perforationprocess and this cement or material must be cleared out of theperforations to increase the flow of oil or gas through theperforations. Additionally, as oil or gas is produced from the reservoirthrough these perforations, material and paraffin contained in the oilmay start to fill up the perforations and will have to be cleared out ofthe perforations at various intervals to keep effectively producing oilor gas from the reservoir.

There are a number of different prior art methods for cleaning andstimulating wells, however, they often suffer from drawbacks or are notas effective as they could be.

SUMMARY OF THE INVENTION

In an aspect, a downhole tool is provided. The downhole tool can includea first stage operative to receive a steady flow of pressurized fluidthough an inlet and discharge a pulsating fluid flow and a second stageconnected to the first stage and operative to receive the pulsatingfluid flow from the first stage and increase the pulsations of the fluidflow before the pulsating fluid flow is discharged out of the secondstage.

In a further aspect, the first stage can include a sub having: agenerally tubular body with a top end and a bottom end; a fluid inlet atthe top end; a single fluid outlet at the bottom end; and a plurality ofpassages fluidly connecting the inlet at the top end and the singleoutlet at the bottom end, the plurality of passages configured to inducepressure pulses in a steady stream of fluid entering the sub through theinlet at the top end and discharge the fluid as a single pulsatingstream through the single fluid outlet.

In a further aspect, the second stage can include a nose. The nose cancomprise: a central bore connected to the inlet in the top end of thenose; and at least one outlet passage extending from the central bore tothe at least one outlet port.

In another aspect, a downhole tool is provided. The downhole tool cancomprise a first stage comprising a sub having: a generally tubular bodywith a top end and a bottom end; a fluid inlet at the top end; a singlefluid outlet at the bottom end; and a plurality of passages fluidlyconnecting the inlet at the top end and the single outlet at the bottomend, the plurality of passages configured to induce pressure pulses in asteady stream of fluid entering the sub through the inlet at the top endand discharge the fluid as a single pulsating stream through the singlefluid outlet; and a second stage connected to the first stage, thesecond stage comprising a nose having: a top end; a bottom end; an inletprovided in the top end of the nose to receive the pulsating fluid flowfrom the first stage; and at least one port is provided in the bottomend of the nose, wherein the top end of the nose has external threadsand the top end of the nose mates with the bottom end of the sub to forma pulsation chamber, and wherein the inlet in the top end of the nose isin fluid communication with the pulsation chamber, and wherein the atleast one port of the nose is in fluid communication with the pulsationchamber.

A well tool can be used to stimulate a well including chemical injectionand near well bore perforation clean out. The well tool can include anumber of stacked stages where each stage functions to create pulsationsin a fluid stream causing the fluid stream to rapidly cycle between highand low pressure (impulses) before the fluid stream is discharged fromthe well tool as a number of pulsating fluid streams directed towardsthe walls of the well bore. These pulsating fluid streams directed atthe walls of the well bore can induce high velocity stresses on the wellbore casing near the well tool and induce high frequency low amplitudedisplacement forces peripherally in the distal areas of reservoir whenthe well tool is used in a semi-permanent continuous configuration toclean perforations and mobilize fluid through the reservoir channels.The resulting forces both in the near well bore and periphery result ina dynamic state of enhanced fluid—chemical dispersion and mobilizationin order to improve productivity in the well (Enhanced OilRecovery—EOR).

The well tool can be conveyed in the well either as a drop tool andtubing string arrangement or coil tubing conveyed. The well tool canwork well in both low volume (0.5 BBL/min) and high volume applications(5.0 BBL/min) depending on the specific application and well conditions.

This tool is easy to handle and plugs off less during field operationsthan other tools due to the synergistic nature of the multi-stagestacked design. The tool does not require large vehicle transport fromjob to job and is easily and efficiently assembled. The tool may havethe external diameter modified to fit the well application, eitherlarger or smaller. The smaller tool has an outer diameter such that itcan be operated in well casings having a fairly small size so as to workin a range of sizes that are found in most producing wells.

DESCRIPTION OF THE DRAWINGS

A preferred embodiment of the present invention is described below withreference to the accompanying drawings, in which:

FIG. 1 illustrates a side sectional view of a downhole well conditioningtool;

FIG. 2 illustrates the downhole well conditioning tool of FIG. 1separated into a sub and a nose;

FIG. 3 illustrates a side view of the nose;

FIG. 4 illustrates front view of the nose of FIG. 3;

FIG. 5 illustrates a side view of an alternate nose;

FIG. 6 illustrates a side sectional view of the nose of FIG. 5; and

FIG. 7 illustrates a sectional view of the nose taken along line AA inFIG. 6.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

FIGS. 1 and 2 illustrates a well tool 10 that is used down hole and canself-create pulsating fluid streams for well cleaning and stimulation.The well tool 10 can be suspended downhole in a well (not shown), suchas an oil well. Typically, the well tool 10 will be suspended downholeon a running string, as a drop tool, or coiled tubing configurationrunning to the ground surface. Pressurized fluid can be forced down therunning string or coiled tubing into the well tool 10 where thepressurized fluid stream will be self-excited in the well tool 10 beforeexiting the well tool 10 through outlet ports 83, 85, 87 as pulsatingpressurized fluid streams to contact the inside surfaces of the well andalso displace fluid distally in both the near well bore and theperipheral reservoir.

In a typical application, the well tool 10 can be lowered downhole sothat the well tool 10 is located at a point in the well whereperforations have been made in the casing of the well. Theseperforations will usually be made by conventional means, such as by useof a perforation gun, and will extend through the casing of the well andthe cement holding the casing in place and into the formation behind thewell casing. These perforations through the well casing allowhydrocarbons in the formation to pass through the perforations in thewell casing and enter the well casing so that the hydrocarbon can beremoved from the well casing to the ground surface.

Commonly, these perforations may not be as open as they could be. Theinitial perforation could have debris left in it from the perforation,be plugged from drilling material from the drilling process orparticulate material from drilling fluid, etc. Additionally, during theproduction of hydrocarbons from the well, a buildup of scale, paraffinwax and asphaltenes in the perforations can reduce the amount ofhydrocarbon that can flow through the perforations or this build upcould even plug the perforations completely.

The well tool 10 can be lowered down hole and positioned proximate theperforations in the well. Pressurized fluid, such as water, chemicals, amixture of water and chemicals or even a gas or mixture of gases at anysuitable temperatures (in one aspect, steam could be pumped down thestring or coiled tubing), can be pumped down the string or coiled tubingto the well tool 10 ideally as a steady pressurized stream. Once in thewell tool 10, the pressurized fluid stream will be self-exited in atwo-stage stacked process into a pulsating pressurized fluid stream andejected out of the well tool 10 through the outlet ports 83, 85, 87.This pulsating pressurized fluid stream will be directed by the outletports 83, 85, 87 towards the perforations in the well casing to try andremove material from the perforations and unplug them. These pulsatingfluid streams can disturb the walls of the perforations to remove debrisfrom the perforations and displace any impermeable skin on the walls ofthe perforation tunnels. The pressure alterations and resonance wavescreated by the fluid streams can displace skin debris and fluid both inthe near well bore and distally through the reservoir. Additionally,these pulsating pressurized fluid streams can reduce the impact of thewell tool 10 plugging during operation.

These pulsating streams can take the form of streams of fluid exitingthe outlet ports 83, 85, 87 where the pressure in the stream rapidlycycles between higher and lower pressure. Typically, the cycling of thepressure of the streams will occur substantially simultaneously in eachof the streams exiting from the different outlet ports 83, 85, 87. Inone aspect, although to the naked eye the streams will appear likerelatively steady streams, closer examination (such as through slowmotion capture) will show the streams can be formed of numerous fluiddroplets forming the streams. The well tool 10 can produce a high volumeand high pressure ejection pattern (800-900 psi) and high frequencypulsations as they exit the discharge nozzle (100-400) cycles persecond.

The construction and arrangement of the well tool 10 is such that theannular volume between the well tool 10 and the well casing can berelatively small (depending on the size of the well tool 10 and thediameter of the well casing) which can concentrate the pressurefluctuations of the fluid streams in a manner that can significantlydamage the skins (debris, paraffin, ashphaltenes, etc.) that may beobstructing the well bore perforations resulting in the removal of theobstruction, opening channels in the reservoir and further enhancing thedisplacement of chemistries intended to enhance oil recovery and improvelong term well productivity results.

In one aspect, the well tool 10 may have a small enough outer diameterso that it can be run into the well on a tubing string, through theproduction tubing as a drop tool or on a coil tubing configuration.

The well tool 10 can have a sub 20 and a nose 60 and these componentstogether can define a first pulse creating section 90 and a second pulsecreating section 92.

The sub 20 can have a generally tubular shaped body with an open endedand externally threaded top end 22 and a internally threaded bottom end24. The sub 20 can have a number of internal passages to cause anideally steady pressurized stream of fluid entering the sub 20 through afluid inlet 30 to become self-excited before entering a pulsationchamber 52 from a central passage 50 as a pulsating pressurized fluidflow. These passages between the fluid inlet 30 and the central passage50 can define the first pulse creating section 90 of the well tool 10.

The fluid inlet 30 leads to a nozzle 32 that directs the flow ofpressurized fluid into a first chamber 34. From the first chamber 34,two diffuser passages 36, 38 angle outwards towards the outside edges ofthe sub 20 at an angle from a central axis of the sub 20. A wedge-shapedsplitter 40 can be formed between the two diffuser passages 36, 38 witha flat front surface 42 to split the steady pressurized stream of fluidinto the two diffuser passages 36, 38. A transverse passage 44 can beprovided connecting the two diffuser passages 36, 38 downstream fromwhere the splitter 40 has split the flow of fluid into the two diffuserpassages 36, 38. Opposite ends of the transverse passage 44 open intothe two diffuser passages 36, 38, respectively.

Downstream from the transverse passage 44, the diffuser passages 36, 38stop angling outwards from the central axis of the sub 20 and changedirection to angle inwards towards the central axis of the sub 20 untilthe two diffuser passages 36, 38 meet in a central passage 50 beforeexiting into the pulsation chamber 52.

The orientation of the passages will cause the steady fluid streamentering the well tool 10 through the fluid inlet 30 to oscillatebetween the first diffuser passage 36 and the second diffuser passage38. The steady pressurized fluid stream entering the fluid inlet 30 willbe accelerated through the nozzle and into the first chamber 34. Insteadof the splitter 40 splitting this accelerated fluid flow into two steadyfluid streams with each steady fluid stream being directed down one ofthe two diffuser passages 36, 38, the relative positioning of thesplitter 40, the diffuser passages 36, 38 and the transverse passage 40causes the steady pressurized fluid stream to oscillates (or alternate)between first flowing through the first diffuser passage 36 and then thesecond diffuser passage 38 before once again flowing through the firstdiffuser passage 36. Instead of the steady flow being split by thesplitter 40 between the two diffuser passages 36, 38, most of the fluidflow will tend to enter only one of the diffuser passages 36, 38 whilelittle fluid will enter the other diffuser passage 38, 36. As the fluidstream flows down the first diffuser passage 36 (for example), theleading edge 42 of the splitter 40 will direct some of the fluid flowinto a vortex that forms at the opening of the second diffuser passage38. This vortex will discourage the flow of the fluid into the seconddiffuser passage 38 causing most of the fluid flow to be directed intothe first diffuser passage 36.

The flow of the fluid stream through the first diffuser passage 36 willtend to continue until the flow is disturbed, causing the fluid streamto start flowing through the second diffuser passage 38 instead. Thisneeded disturbance is created by the transverse passage 44 connectingthe two diffuser passages 36, 38 downstream from the splitter 40. Thefluid stream passing the by the transverse passage 44 as it flows downthe first diffuser passage 36 will cause a vacuum (negative pressurecondition) in the transverse passage 44. This negative pressurecondition is communicated through the transverse passage 44 to thesecond diffuser passage 38 where it can disrupt the vortex blocking theentry of the second diffuser passage 38 and then this negative pressurein the second diffuser passage 38 can pull the fluid stream into thesecond diffuser passage 38. As the fluid stream begins to flow throughthe second diffuser passage 38 a vortex will be created in front of theinlet to the first diffuser passage 36 which will block the fluid streamfrom flowing through the first diffuser passage 36. As the fluid streamcontinues to flow through the second diffuser passage 38 a reducedpressure condition will occur in the transverse passage 44 and therebyreduce the pressure in the first diffuser passage 36 which in turn willeventually disrupt the vortex at the inlet of the first diffuser passage36 and cause the flow to once again begin flowing through the firstdiffuser passage 36 rather than the second diffuser passage 38. A vortexwill once again be created before the inlet to the second diffuserpassage 38 which will direct the flow into the first diffuser passage36.

In this manner, the steady pressure flow stream will alternate betweenflowing through the first diffuser passage 36 and the second diffuserpassage 38 causing a high frequency oscillation of the fluid streambetween these two diffuser passages 36, 38, with the stream of fluidalternating between mostly flowing through the first diffuser passage 36and then mostly flowing through the second diffuser passage 38.

Rather than keeping these oscillating fluid streams separate in the welltool 10, the first diffuser passage 36 and the second diffuser passage38 change direction and begin to angle inward downstream from thetransverse passage 44 until the diffuser passages 36, 38 once again joinin the central passage 50. The effect to the two oscillating fluidstreams being joined in the central passage 50 results in a single fluidstream in the central passage 50 that is cyclically fluctuating inpressure (pulsating) rather than oscillating, with the velocity andpressure of the fluid stream increased and decreasing as it passesthrough the central passage 50.

From the central passage 50 the self-excited pulsating fluid streampasses into the second pulse creating section 92 of the well tool 10 andthe pulsating fluid stream from the first pulse creating section 90 canbe enhanced in this second pulse creating section 92. The second pulsecreating section 92 is formed by both a portion of the sub 20 and thenose 60 and includes a pulsation chamber 52 formed by the connection ofthe nose 60 to the sub 20 and a central bore 70 leading out of thepulsation chamber 52.

FIGS. 3 and 4 show the nose 60. The nose 60 can have a generally tubularshape oriented around a central axis with a semi-spherical shaped bottomend 64. When the nose 60 is connected to the sub 20, the central axis ofthe nose 60 can be aligned with the central axis of the sub 20. The nose60 can have a top end 62 that has external threads mating with theinternal threads on the bottom end 24 of the sub 20. The top end 62 ofthe nose 60 can have a circular flat central portion 72 surrounding theinlet of the central bore 70. A tapered shoulder 74 can extend downwardsand outwards from the circular flat central portion 72 to a flatshoulder 76 surrounding the circular flat central portion 72 and thetapered shoulder 74. The flat shoulder 76 can extend from the base ofthe tapered shoulder 74 to the outer diameter of the top end 62 of thenose 60.

The central bore 70 can extend along the central axis of the nose 60. Anumber of outlet passages 82, 84, 86 can extend outwards from thecentral bore 70 to outlet ports 83, 85, 87. These outlet passage 82, 84,86 can extend downwards and outwards from the central bore 70 at anangle to the central axis of the nose 60, until they end in the outletports 83, 85, 87.

Referring to FIGS. 5, 6 and 7 an alternative nose 160 is shown. Likenose 60 shown in FIGS. 3 and 5, the nose 160 can have a generallytubular shape oriented around a central axis with a semi-sphericalshaped bottom end 164. When the nose 160 is connected to the sub 20, thecentral axis of the nose 160 can be aligned with the central axis of thesub 20. The nose 160 can have a top end 162 that has external threadsmating with the internal threads on the bottom end 24 of the sub 20.

Unlike the nose 60, nose 160 can have a tapered shoulder 174 surroundingan inlet of a central bore 170. The tapered shoulder 174 can extenddownwards and outwards to a flat shoulder 176 surrounding the taperedshoulder 174. The flat shoulder 176 can extend from the base of thetapered shoulder 174 to the outer diameter of the top end 162 of thenose 160.

The central bore 170 can extend along the central axis of the nose 160and a number of outlet passages 182 can extend radially outwards fromthe central bore 170 to outlet ports 183.

These outlet passage 182 can extend downwards and outwards from thecentral bore 170 at an angle to the central axis of the nose 160, untilthey end in the outlet ports 183.

Unlike nose 60 which where the outlet passages 82, 84, 86 will directthe pulsating fluid stream exiting the nose 60 downwards and outwardsagainst the wall of a well, the outlet passages 182 extending radiallyin the nose 160 will direct the pulsating fluid stream discharged fromthe nose 60 substantially perpendicular to central axis of nose 160 andagainst the walls of the well.

Referring again to FIGS. 1-4, the second pulse creating section 92 ofthe well tool 10 will take the pulsating stream from the central passage50 and further enhance the pulsation of this pressurized fluid stream.When the top end 62 of the nose 60 (or the nose 160) is threaded intothe bottom end 24 of the sub 20 the pulsation chamber 52 is formed. On atop end of this pulsation chamber 52 the central passage 50 will enterinto the pulsation chamber 52 and therefore the pulsating pressurizedfluid stream will enter into the pulsation chamber 52. The pulsations ofthis pressurized fluid stream will be amplified by the pulsation chamber52 before passing into the central bore 70 and eventually out the outletpassages 82, 84, 86 and the outlet ports 83, 85, 86. The outlet ports83, 85, 86 can have different outlet configurations to optimize theireffectiveness in different well bore configurations and depending on thefluid (water, chemicals, gas, steam, etc.) used.

The pulsation chamber 52 can be symmetrical around the central axis ofthe nose 60 and the sub 20, but the pulsation chamber 52 can have alarger diameter than the central passage 50 feeding into it resulting inthe velocity of the fluid in the pulsation chamber 52 being much lowerthan the velocity of the pulsating fluid stream entering the pulsationchamber 52 from the central passage 50. The faster moving pulsatingpressurized fluid stream exiting the central passage 50 meeting theslower moving fluid in the pulsation chamber 52 causes vortices to formin the pulsation chamber 52 as a result of the shear forces created whenthe fast moving fluid stream meets the slower moving fluid in thepulsation chamber 52. Because the central passage 50 is round, thevortices take the form of a circle in the pulsation chamber 52 and forma vortex ring encircling the inlet to the central bore 70. The circularflat central portion 72 and the tapered shoulder 74 can help to formthis vortex ring. The vortex ring formed around the inlet of the centralbore 70 will cause periodic pressure pulses in the fluid in thepulsation chamber 52. These pressure pulses will propagate upstream towhere the incoming pulsating fluid stream shears with the fluid in thepulsation chamber 52 and induce vorticity fluctuations. This causesstrong fluctuations in pressure of the fluid contained in the centralbore 70 which in turn causes rapidly cycling of the fluid pressure inthe fluid streams (a pulsed or pulsating jet of fluid) exiting thecentral bore 70 through the outlet passages 82, 84, 86. The foregoing isconsidered as illustrative only of the principles of the invention.Further, since numerous changes and modifications will readily occur tothose skilled in the art, it is not desired to limit the invention tothe exact construction and operation shown and described, andaccordingly, all such suitable changes or modifications in structure oroperation which may be resorted to are intended to fall within the scopeof the claimed invention.

1. A downhole tool comprising: a first stage operative to receive asteady flow of pressurized fluid though an inlet and discharge apulsating fluid flow; and a second stage connected to the first stageand operative to receive the pulsating fluid flow from the first stageand increase the pulsations of the fluid flow before the pulsating fluidflow is discharged out of the second stage.
 2. The downhole tool ofclaim 1 wherein pulsating fluid flow discharged from the second stage isdischarged at an angle to a centerline of the first second stage.
 3. Thedownhole tool of claim 1 wherein the first stage comprises a sub having:a generally tubular body with a top end and a bottom end; a fluid inletat the top end; a single fluid outlet at the bottom end; and a pluralityof passages fluidly connecting the inlet at the top end and the singleoutlet at the bottom end, the plurality of passages configured to inducepressure pulses in a steady stream of fluid entering the sub through theinlet at the top end and discharge the fluid as a single pulsatingstream through the single fluid outlet.
 4. The downhole tool of claim 3wherein the top end has external threads and the bottom end has internalthreads.
 5. The downhole tool of claim 3, wherein the sub furthercomprises: a first chamber immediately downstream from the fluid inlet;two diffuser passages having openings in the first chamber, eachdiffuser angling outwards from a central axis of the sub as the twodiffuser passages extend from the first chamber; a transvers passagerunning between the two diffuser passages and opening into each of thetwo diffuser passages; and a single central passage, both of thediffuser passages exiting into the single central passage, the singlecentral passage connected to the single fluid outlet at the bottom endof the sub, wherein the two diffuser passages change direction and anglein towards the central axis of the sub downstream from the transversepassage.
 6. The downhole tool of claim 5 wherein the sub furthercomprises a wedge shaped splitter formed between the two diffuserpassages.
 7. The downhole tool of claim 6 wherein the wedge shapedsplitter having has a flat front surface.
 8. The downhole tool of claim1 wherein the second stage comprises a nose having a top end and abottom end.
 9. The downhole tool of claim 8 wherein an inlet is providedin the top end of the nose to receive the pulsating fluid flow from thefirst stage and at least one port is provided in the bottom end of thenose.
 10. The downhole tool of claim 8 wherein the bottom end of thenose has a semi-spherical shape.
 11. The downhole too of claim 4 whereina top end of the nose has external threads and the top end of the nosemates with the bottom end of the sub to form a pulsation chamber. 12.The downhole tool of claim 11 wherein the inlet in the top end of thenose is in fluid communication with the pulsation chamber.
 13. Thedownhole tool of claim 11 wherein the nose further comprises: a centralbore connected to the inlet in the top end of the nose; and at least oneoutlet passage extending from the central bore to the at least oneoutlet port.
 14. The downhole tool of claim 13 wherein the central boreof the nose extends along a central axis of the nose.
 15. The downholetool of claim 13 wherein the central bore of the nose is aligned withthe central axis of the nose.
 16. The downhole tool of claim 13 whereinthe top end of the nose has a circular flat central portion surroundingthe inlet.
 17. The downhole tool of claim 16 wherein a tapered shoulderis provided extending downwards and outwards from the circular flatcentral portion on the top end of the nose to a flat shouldersurrounding the circular flat central portion and the tapered shoulder.18. The downhole tool of claim 17 wherein the flat shoulder extends froma base of the tapered shoulder to an outer diameter of the nose.
 19. Thedownhole tool of claim 13 wherein the at least one outlet passageextends downwards from where the at least one outlet passage connectswith the central bore and at an angle to the central axis of the nose.20. The downhole tool of claim 13 wherein the at least one outletpassage extends substantially radially outwards from where the at leastone outlet passage connects with the central bore.
 21. The downhole toolof claim 12 wherein the pulsation chamber is symmetrical around acentral axis of the nose.
 22. The downhole tool of claim 13 wherein thepulsation chamber has a larger diameter than the central bore.
 23. Thedownhole tool of claim 11 wherein the central axis of the sub is alignedwith the central axis of the nose.
 24. The downhole tool of claim 18wherein the external threads are provided on the outer diameter of thenose.
 25. A downhole tool comprising: a first stage comprising a subhaving: a generally tubular body with a top end and a bottom end; afluid inlet at the top end; a single fluid outlet at the bottom end; anda plurality of passages fluidly connecting the inlet at the top end andthe single outlet at the bottom end, the plurality of passagesconfigured to induce pressure pulses in a steady stream of fluidentering the sub through the inlet at the top end and discharge thefluid as a single pulsating stream through the single fluid outlet; anda second stage connected to the first stage, the second stage comprisinga nose having: a top end; a bottom end; an inlet provided in the top endof the nose to receive the pulsating fluid flow from the first stage;and at least one port is provided in the bottom end of the nose, whereinthe top end of the nose has external threads and the top end of the nosemates with the bottom end of the sub to form a pulsation chamber, andwherein the inlet in the top end of the nose is in fluid communicationwith the pulsation chamber, and wherein the at least one port of thenose is in fluid communication with the pulsation chamber.